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Chronic myeloid leukemia (CML) is characterized by formation of the BCR-ABL fusion gene, usually as a consequence of the Philadelphia (Ph) translocation between chromosomes 9 and 22. Large deletions on the derivative chromosome 9 have recently been reported, but it was unclear whether deletions arose during disease progression or at the time of the Ph translocation. Fluorescence in situ hybridization (FISH) analysis was used to assess the deletion status of 253 patients with CML. The strength of deletion status as a prognostic indicator was then compared to the Sokal and Hasford scoring systems. The frequency of deletions was similar at diagnosis and after disease progression but was significantly increased in patients with variant Ph translocations. In patients with a deletion, all Ph+ metaphases carried the deletion. The median survival of patients with and without deletions was 38 months and 88 months, respectively (P = .0001). By contrast the survival difference between Sokal or Hasford high-risk and non-high-risk patients was of only borderline significance (P = .057 and P = .034). The results indicate that deletions occur at the time of the Ph translocation. An apparently simple reciprocal translocation may therefore result in considerable genetic heterogeneity ab initio, a concept that is likely to apply to other malignancies associated with translocations. Deletion status is also a powerful and independent prognostic factor for patients with CML. The prognostic significance of deletion status should now be studied prospectively and, if confirmed, should be incorporated into management decisions and the analysis of clinical trials. (C) 2001 by The American Society of Hematology.

Until recently the ability to analyze complex karyotypic rearrangements was totally dependent upon light microscopy of G-banded chromosomes. Developments in the area of molecular cytogenetics have revolutionized such analysis, making it possible to determine the nature of complex rearrangements. An extensive analysis has been made of the small cell lung carcinoma (SCLC) cell line U2020, using a combined approach of conventional and molecular cytogenetics, enabling a highly detailed karyotype to be constructed revealing rearrangements previously undetected by G-banding alone. This approach offers the opportunity to reassess other tumor karyotypes, particularly those of high complexity found in solid tumors, for tumor-specific consistent rearrangements indecipherable by conventional karyotyping.

This review focuses on polycythemia vera (PV)-its diagnosis, cellular and genetic pathology, and management. In Section I, Dr. Pearson, with Drs. Messinezy and Westwood, reviews the diagnostic challenge of the investigation of patients with a raised hematocrit. The suggested approach divides patients on their red cell mass (RCM) results into those with absolute (raised RCM) and apparent (normal RCM) erythrocytosis. A standardized series of investigations is proposed for those with an absolute erythrocytosis to confirm the presence of a primary (PV) or secondary erythrocytosis, with abnormal and normal erythropoietic compartments respectively, leaving a heterogenous group, idiopathic erythrocytosis, where the cause cannot be established. Since there is no single diagnostic test for PV, its presence is confirmed following the use of updated diagnostic criteria and confirmatory marrow histology. In Section II, Dr. Green with Drs. Bench, Huntly, and Nacheva reviews the evidence from studies of X chromosome inactivation patterns that support the concept that PV results from clonal expansion of a transformed hemopoietic stem cell. Analyses of the pattern of erythroid and myeloid colony growth have demonstrated abnormal responses to several cytokines, raising the possibility of a defect in a signal transduction pathway shared by several growth factors. A number of cytogenetic and molecular approaches are now focused on defining the molecular lesion(s). In the last section, Dr. Barbui with Dr. Finazzi addresses the complications of PV, notably thrombosis, myelofibrosis and acute leukemia. Following an evaluation of published data, a management approach is proposed. All patients should undergo phlebotomy to keep the hematocrit (Hct) below 0.45, which may be all that is required in those at low thrombotic risk and with stable disease. In those at high thrombotic risk or with progressive thrombocytosis or splenomegaly, a myelosuppressive agent should be used. Hydroxyurea has a role at all ages, but (32)P or busulfan may be used in the elderly. In younger patients, interferon-alpha or anagrelide should be considered. Low-dose aspirin should be used in those with thrombotic or ischemic complications.

The molecular basis for blast transformation of chronic myeloid leukemia (CML) remains poorly understood. Cytogenetic alterations associated with CML blast crisis have previously been extensively studied by conventional G-banding analysis. However the complexity of some chromosome abnormalities or poor chromosome morphology or both has exceeded the resolution of G-banding analysis in a significant proportion of CML cases, and complex chromosome rearrangements have remained unidentified. In this study, comparative genomic hybridization (CGH) was used to elucidate genome imbalances in chronic phase or blast crisis samples or both from 12 CML patients. CGH and G-banding results were compared, and discrepancies were further clarified by using multipaint chromosome analysis and locus-specific DNA probes. No imbalances were detected in the 4 early disease phase samples studied. Eleven blast crisis samples were analyzed by G-banding and CGH, and the commonest genomic abnormality detected was overrepresentation of the long arm of chromosome 8, which was detected in 5 patients. This overrepresentation was attributable to trisomy 8 in 4 patients, whereas amplification of the entire long arm of chromosome 8 was detected in 1 patient. The formation of isochromosomes of the long arm of chromosome 8 was observed as a mechanism for gene amplification in this patient. Additional material originating from chromosome 8 was also observed intercalated into three marker chromosomes in peripheral blood metaphase spreads from this patient. These markers may further define areas on chromosome 8 that harbor oncogenes implicated in transformation of chronic myeloid leukemia.

Aims: The aim of this study was to analyse the immunophenotypic and molecular features of a large series of follicular lymphomas, focusing in particular on atypical cases that fail to express CD10 and/or bcl-2. Such cases present diagnostic pitfalls, especially with regard to the differential diagnosis from follicular hyperplasia and marginal zone B-cell lymphoma. Therefore, we also included an immunohistochemical evaluation of stathmin, which is strongly expressed by germinal centre B cells, as a putative new marker for follicular lymphomas, particularly those with an atypical phenotype. Methods and results: Two hundred and five follicular lymphomas were investigated with immunohistochemistry and fluorescence in-situ hybridization (FISH). The use of three distinct anti-bcl-2 antibodies together with CD10 expression data and FISH analysis for bcl-2 and bcl-6 rearrangements allowed subclassification of follicular lymphoma into four distinct subgroups: (i) CD10-positive/bcl-2-positive, (ii) CD10-positive/bcl-2-negative, (iii) CD10-negative/bcl-2-positive, and (iv) CD10-negative/bcl-2-negative. All cases were bcl-6-positive. STMN1 (stathmin) was shown to be helpful in diagnosing bcl-2-negative and/or CD10-negative follicular lymphomas, and in their distinction from marginal zone B-cell lymphoma. Conclusions: Combined immunohistological and molecular analyses reveal that follicular lymphomas showing an atypical immunophenotypic and molecular profile exist, and we demonstrate that STMN1 represents a novel useful diagnostic marker for these. © 2013 Blackwell Publishing Ltd.